Well played, Snapchat.
In the past few years we've seen the "ephemeral app for sexting with friends" (intentional or not, the greatest PR ever) expand into messaging (with Snapchat Chat), story-telling (with My and Our Stories), and now more utilitarian functionality (with Snapcash).
The monetization opportunity it is obvious here but Snapcash feels like a less "obvious" extension of the platform. Of all the things you could have built, why this, @evanspiegel?

@rrhoover hey! I used to be a financial technology Reporter and may be able to help. Not answering for Snapchat, but I've been asking some tech companies and payments experts to find out why all of these companies are interested in payments (Facebook, Twitter, Snapchat, and others are all getting into e-commerce/P2P payments). Payments is a low margin industry so it's hard to actually make money unless you have a massive user base, which makes it even weirder than all these companies want to enter payments. Basically there are two reasons:
It "closes the loop"-- this means that ad platforms (fb and Twitter) that have buy buttons for Goods/services will be able tell advertisers of users are actually purchasing things, or just clicking on the advertisement.
The second is pretty simple -- it should make people more dedicated to your service. It's kinda hard to see if that's true without data.
Hope that helps!

@rrhoover to me it feels like snapchat is grasping at straws to find a monetization strategy. You see a hint of it when they do special event stories and messages sent from "teamsnapchat". It just doesn't seem like a good fit for me. I think it may take away from the core functionality of the app and also pose a major security risk. Snapchat as already seen their fair share of security breaches so I would be weary to take on the responsibility of something like this. Snapchat is so awesome as-is, I would just be careful adding in new functionality.

Payments - in theory, and in practice in China - are a huge part of the messaging endgame. Exciting/interesting to see Snapchat aggressively throwing in their hat early on.
Not sure if Square would have been the partner I'd have chosen here, but maybe this will be their time to shine
Snapcash starts sounding super interesting when compounded with Snapchat's recent efforts in the live event space (Our Story, etc). You don't have to be a soothsayer to see something swirling around real-time payments, events, venues, music - the ingredients are all there.
Last thing is how formidable Snapchat is proving to be as a company interested in creative partnerships/integrations that some of its more entrenched competitors cannot strategically afford to partake in. Advantages of being the new kid, indeed.